The Eighth Wonder of the World - Part Four

 

 Eighth Wonder of the World

There are a few considered for the title.

Three are listed here. They are constructions rather than natural wonders.

Pre-1900 creations

Part Four

Great Wall of China

By Jakub Hałun - Own work, CC BY-SA 3.0, httpscommons.wikimedia.orgwindex.phpcurid=6909926

The Great Wall of China is a series of fortifications that were built across the historical northern borders of ancient Chinese states and Imperial China as protection against various nomadic groups from the Eurasian Steppe. Several walls were built from as early as the 7th century BC, with selective stretches later joined by Qin Shi Huang (220–206 BC), the first emperor of China. Little of the Qin wall remains. 

1907

Later on, many successive dynasties built and maintained multiple stretches of border walls. The best-known sections of the wall were built by the Ming dynasty (1368–1644).

A controversial question is whether the wall is visible from low Earth orbit (an altitude of as little as 160 km (100 mi)). NASA claims that it is barely visible, and only under nearly perfect conditions; it is no more conspicuous than many other human-made objects.

By Severin.stalder, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=39661035

Kinzua Bridge

The Kinzua Bridge or the Kinzua Viaduct was a railroad trestle that spanned Kinzua Creek in McKean County in the U.S. state of Pennsylvania. The bridge was 301 feet (92 m) tall and 2,052 feet (625 m) long. Most of its structure collapsed during a tornado in July 2003.

The original Kinzua Bridge, before its reconstruction in 1900

Billed as the "Eighth Wonder of the World", the wrought iron original 1882 structure held the record for the tallest railroad bridge in the world for two years. In 1900, the bridge was dismantled and simultaneously rebuilt out of steel to allow it to accommodate heavier trains. 

Restoration of the bridge began in 2002, but before it was finished a tornado struck the bridge in 2003, causing a large portion of the bridge to collapse. 

The Leaning Tower of Pisa 

The Leaning Tower of Pisa is freestanding bell tower, of Pisa Cathedral. It is known for its nearly four-degree lean, the result of an unstable foundation. The tower is one of three structures in the Pisa's Cathedral Square (Piazza del Duomo), which includes the cathedral and Pisa Baptistry.

By Arne Müseler / www.arne-mueseler.com, CC BY-SA 3.0 de,
https://commons.wikimedia.org/w/index.php?curid=116752074

The height of the tower is 55.86 metres (183 feet 3 inches) on the low side and 56.67 m (185 ft 11 in) on the high side. The tower has 296 or 294 steps.

The tower began to lean during construction in the 12th century, due to soft ground which could not properly support the structure's weight. Construction of the tower occurred in three stages over 199 years.  It worsened through the completion of construction in the 14th century. By 1990, the tilt had reached 5.5 degrees.

I visited it in 1989. Walking up it's spiral staircase was a bizarre experience. You went up on one side and it felt like you were going down on the other. 

By Arne Müseler / www.arne-mueseler.com, CC BY-SA 3.0 de, https://commons.wikimedia.org/w/index.php?curid=116752044

Galileo Galilei, who lived in Pisa at the time, is said to have dropped two cannonballs of different masses from the tower to demonstrate that their speed of descent was independent of their mass, in keeping with the law of free fall. 

The structure was stabilized by remedial work between 1993 and 2001, which reduced the tilt to 3.97 degrees.

More in this Series

Next week, that crazy Flaw Finding Phil. A video/audio story.

Have a great week
Peace.